Abstract

he cichlid fishes comprise the largest extant vertebrate family and are the quintessential example of rapid “explosive” adaptive radiations and phenotypic diversifications. Despite the relative genomic homogeneity, cichlids harbour a spectacular intra- and interspecific diversity in morphology, behaviour, and ecological specialisation. Akin to other vertebrates, a considerable proportion of cichlid phenotypic diversity involves structures derived from a common progenitor cell population – the neural crest (NC). These include distinctive pigmentation patterns and a vast variation in craniofacial morphologies.

To investigate the role of NC in morphological evolution of East African cichlids, we compared the embryonic and NC development between three phenotypically divergent cichlid species (Astatotilapia calliptera, Rhamphochromis sp. ‘chilingali’ and Tropheops sp. ‘mauve’) endemic to Lake Malawi and its basin. Our results revealed interspecific variability in many features of embryogenesis that could potentially influence the concomitant formation of the NC and its derivatives. By investigating the migratory behaviour of NC cells across their ontogeny, we identified striking temporal and spatial variation. To further explore the differences in morphogenesis of the NC, we are combining novel 3D morphometrics approaches with transcriptomic and regulatory analyses at most divergent stages of NC development between the study species.